Sink mat



FIG. 1 is a perspective view of a sink mat showing my new design.

FIG. 2 is a right side view thereof, a left side view being a mirror image.

FIG. 3 is a front view thereof, a rear view being a mirror image.

FIG. 4 is a top view thereof; and,

FIG. 5 is a bottom view thereof.

The broken lines show portions of the design that form no part of the claimed design. 

CLAIM The ornamental design for a sink mat, as shown and described. 